In their winning bid to host the 2028 Summer Olympics, Los Angeles leaders pledged that the city’s version of the Games would be the greenest ever — a goal they planned to achieve in large part by making access to the event “car-free.”

It was a bold statement because, well, it’s Los Angeles. Could America’s capital of car culture, where traffic shapes daily life more than the weather, really pull that off?

Now that the Paris Olympics have ended, the clock is ticking. Los Angeles must complete much-needed upgrades to the region’s transit system to handle an influx of athletes and visitors without bringing car traffic to a standstill. That includes extending rail lines, adding a legion of buses and clearing countless traffic lanes to allow hundreds of thousands of people to navigate a metropolis that sprawls across 4,000 square miles.

“I’m optimistic,” said Eli Lipmen, the executive director of Move L.A., an organization that advocates for the expansion of public transit in the region. “There’s nothing better than a deadline.”

At the closing ceremony on Sunday, Mayor Karen Bass received the official Olympic flag to mark the official countdown to the 2028 Games. And on Saturday at a news conference in Paris, she reiterated that those Games would be “no-car.”

But in some ways, the dream of a car-free — or, as organizers have been putting it more recently, “transit-first” — Olympics in Los Angeles may feel even more out of reach than it did seven years ago, when it was named the host city for the third time.